Spiral sheet-metal pipe.



T. SILK.

SPIRAL SHEET METAL PIPE.

APPLICATION FILED DEC.27. 1915.

Patented Apr. 16, 1918.

2 SHEETS-SHEET I.

INVEN ATTOPN EY k T. SILK. sPlR'AL SHEET METAL PIPE.

APPLICATION FILED DEC. 27. 1915- I 1, %353,3Q, Patented Apr. 16, 1918.

2 SHEETS-SHEET 2.

WW I ATTORNEY THOMAS SILK, OF MARTINS FERRY, OHIO.

SPIRAL SHEET-METAL PIPE.

Specification of Letters Patent.

Patented Apr. is, rare.

Application filed December 27, 1915. Serial No. 68,1632.

tain new and useful Improvements in Spiral Sheet-Metal Pipes, of which the following is a specification. r

This invention relates broadly to sheetmetal pipes, and more particularly to a spirally-wound pipe.

The primary object of the invention is to provide a sheet-metal pipe which is so;

formed as to be extremely strong and capable of ,withstanding relatively great strains both internal and external.

A further object is to provide a sheetmetal pip-1 of the spiral type the meeting edges of which are firmly joined by a novel form of seam adapted to elfectually resist strains having a tendency to separate such edges and to permit leakage at the joints; and, further-,a seam adapted to reinforce the pipe to an extent rendering the latter capable of sustaining, without distortion, loads producing high external pressures, as when said pipe is used for culverts, sewers, and the like.

With these and other objects in View, the invention resides in the features of construction which will hereinafter be fully described, reference being had to the accom-' panying drawings, forming a part of this specification, inwhich- Figure 1 is a side elevation of a pipe embodying my invention;

Fig. 2 is an end View of the same;

Fig. 3 is a side elevation of a pipe having a modified form of seam;

Fig. 4 is an end View of the same;

Fig. 5 is a central longitudinal section on line 55, Fig. 2;

Fig. 6 is a detail section of I the seam shown in Fig. 5, showing an inclosing strip or sheath applied thereto;

Fig. 7 is a detail section of theseam in its initial form;

Fig. 8 is a perspective view of a broken section ofthe sheath, removed; and- Fig. 9 is an enlarged section on the line- 99, Fig. 3.

Referring to said drawings, in which like designating characters distinguish like parts throughout the. several views 1 indicates the body of a pipe composed of a single strip of sheet-metal wound or coiled into spiral form, the lateral edges of the strip being interlocked by means of a seam of peculiar novel form. In forming said seam one of the lateral edges of the strip or sheet is turned outward at substantially a right angle to the plane of the sheet, forming an upright flange 2; and the opposite edge of the sheet is bent to provide a substantially U-shaped flange 3, said edge being first turned outward at a right angle to the plane of the sheet toform an outstanding flange of a width substantially double that of the flange 2, after which a return bend is formed near the center line of said outstanding flange.

In forming the pipe, the sheet is coiled into spiral form and the flange 2 of one coil is introduced in the open space between the members of the flange 3 of the adjacent coil, as is shown in Fig. 7. Said engaging flanges are then subjected to the-laterally directed pressure of a shaping tool or mechanism whereby a bead-like crimp 4 is formed in said interengaging flanges, as shown in Figs. 1, .2 and 3, such crimp being designed to firmly interlock said flanges against separation.

As a further reinforcement for the flanges, interlocked as aforesaid, I may employ a sheath 5 for incasing said flanges, said sheath consisting of a separate narrow strip of sheet-metal shaped to fit over and closely embrace said interengaging flanges 2 and. 3. Said sheath is initially of U-shape and is applied to the interengaging flanges prior to the operation of crimping the latter. Then said flanges and said sheath are crimped in a single operation into the form shown in Fig.6.

To provide for the introduction of one end of a pipe section within the end of an adjacent section, that portion of the outstanding seam, formed as hereinbefore described, located adjacent to the ends ofthe pipe is flattened against the pipe, as shown at 6 in Figs. 1 and 2. -As is obvious, the entire seam may, if desired, be turned over against the body of the pipe, as shown at 7 in Figs. 3, 4 and 9; however, when the pipe is to be subjected to external pressure it is preferred that the seam retain its outstandstrength and rigidity. For further increasing the rigidity of the pipe, the sheet or strip composing the body of the pipe is corrugated longitudinally, so that the pipe, when formed, has spirally disposed corrugations 8 formed therein, as shown in Figs. 1, 2 and 5. I

What is claimed is 1. A pipe consisting of a single strip of sheet-metal wound into spiral form, said strip having one edge turned outward to form a flange which stands at substantially a right angle to the plane thereof and having its opposite edge turned outward and shaped to form a Ushaped flange, the said flanges of adjacent spiralsbeing disposed in interengaging relation and having a crimp formed therein whereby they are interlocked, and a sheet-metal sheath disposed in closel embracing relation to and interlocked with said interlocked flanges, said flanges and sheath serving to reinforce said pipe against collapse under external pressure.

2. A pipe consisting of a single strip of sheet-metal wound into spiral form, said strip having one edge turned outward to form a flange which stands at substantially a right angle to the plane thereof and ha"- ing its opposite edge turned outward and shaped to form a U-shaped flange, the said flanges of adjacent spirals being disposed in interengaging relation, a substantially U-shaped sheet-metal sheath disposed in closely embracing relation to the interengaging flanges, said flanges and said sheath having a crimp formed therein for interlocking said parts in assembled relation, said interlocked flanges and sheath constituting an upright spirally disposed seam whereby the pipe is reinforced against collapse under external pressure.

3. A pipe consisting of a single strip of sheet-metal Wound into spiral form, said strip having one edge turned outward to form a flange which stands at substantially a right angle to the plane thereof and having its opposite edge turned outward and shaped to form a U-shaped flange, the said flanges of adjacent spirals being disposed in interengaging relation, and a sheath disposed in closely embracing relation to said interengaging flanges, ,said interengaging flanges and sheath being interlocked by a bead-like crimp formed therein.

In testimony whereof, I affix my signature in presence of two subscribing witnesses.

W. F. KEEPER, H. E. DUNLAP. 

